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Top Reasons Your Plants Don't Bloom

Why don't my (fill in the blank) bloom?

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Gardeners are a pretty patient group, as a whole. We put our faith behind every seed and seedling we plop into the ground, confident that it will eventually look just like the picture on the label. So it's understandable that we become concerned when a couple of months - or years - go by and there are still no flowers. There are many reasons for a lack of flowers, some we can control and others we just have to accept. Here are the top 5 usual suspects, when it comes to why your plant won't bloom.

1. Needs Fertilizer

Photo: © Marie Iannotti
This is the first response of many gardeners. If something isn't flowering, it must need fertilizer, right? Well, maybe. It's true that feeding your plants with a high nitrogen fertilizer will promote lots of green, leafy growth, at the expense of flowers. It's also true that plants need phosphorous to set flower buds. But you need to look at the whole picture.

If your plants look otherwise healthy, check the next 4 items on this list first. If they look show signs of malaise or stress, check all the growing conditions. Is the plant getting plenty of sun (see below) and water? Are there any signs of disease or pests? How do the other plants nearby look? Have you had your soil tested recently. If your soil pH isn't in a good range, it won't matter how much fertilizer you add. Your plants won't be able to access it. All these factors work in combination.

2. Pruning at the Wrong Time

Photo: © Marie Iannotti
When you prune used to be the major culprit in lack of flowers, for shrubs and trees. Pruning plants late in the season can remove all the buds for next year's flowers. Lilacs, forsythia and some hydrangeas can set their buds a year in advance This is becoming less of an issue as new plants are developed that can bloom on new growth. In particular, new hydrangeas that bloom all season, even if you cut them while they're growing, are being introduced every year. But if you have older shrubs and trees that you want to keep, you'll need to know when it's time to hold off on pruning. (link to when to prune)

3. Too Young

Photo: © Marie Iannotti
Most plants are not ready to bloom until they put down roots and had a season or more to mature. Remember, plants don't flower out of vanity. Flowering is how they propagate their species and it takes a lot of energy. Some, like biennials, die shortly after flowering. That's why deadheading before a plant has a chance to set seed can force it to bloom again.

It helps to know something about the type of flower you are growing. Annuals should flower their first year, but it can still take several months for them to mature. You may not see flowers until mid- to late summer. Biennials, like hollyhocks, do not usually bloom at all their first year and then fade away shortly after flowering in their second season. Perennials are being bred to flower more quickly these days. If you are buying large plants, they should be plenty old enough to start blooming the first year you plant them. Even flowering trees and shrubs are being designed with the impatient gardener in mind. But there are plenty of old-fashioned varieties out there that still need to settle in before they hit their stride. Once they do, they should become reliable bloomers.

4. Got Sun?

Photo: © Marie Iannotti
Got Sun? Many flowers require at least 6 hours of sun to set buds. Plants need sun to photosynthesize. This is how they take the raw materials of carbon dioxide and water and turn them into the sugars they need to feed themselves. If they don't get enough sun, they become stressed. One of the first things a stressed plant does is drop its flowers and buds and put all its resources into staying alive. Growth in general will become sparse. The plant will grow tall and gangly and start reaching in the direction of the sun.

Temperature also plays a role in flowering. The warmth of the sun is often what is needed for a flower to open. So the time of day the sun shines on your flower garden also plays a role. Morning light is cooler. Plants with an eastern exposure may only be getting morning sun. Flowers that require "full sun" will bloom more in a western exposure, where they get the hotter afternoon light. Of course there are plants that will wilt or fry in hot afternoon sun, so you really need to research what your plant likes.

5. Winter Damage

Photo: © Marie Iannotti
Weather is the big question mark in every gardening endeavor and lately it seems that winters have become more frustrating than ever. Snow is not usually the problem, since it acts as a great insulator and protection of pants. But cold winters, with no snow cover and harsh, frigid winds, can easily damage or kill flower buds. Dry winters can cause plants to forego flowering, as they go into preservation mode. Wet springs can bring on early fungus diseases and rots.

Warm winters can mean that flowers needing a period of cold to set their flowers buds or to break dormancy, like spring bulbs and peonies, won't get what they need. It can also cause some plants to come out of dormancy early, only to be killed back by a late spring frost or snow storm.

Too cold, not cold enough, too wet, too dry? There's really not much we can do about this other than looking for varieties that are well suited to our area. Even then, there will be seasons when we will just have to roll with the punches.

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